Mental health care is heading towards a crisis in NSW with one quarter of the state's psychiatrists considering leaving the public system this year because of "grossly inadequate" resources and low morale.

The exodus comes amid allegations that some local health authorities are systematically siphoning off mental health resources and refusing to fill key clinical positions so money can be diverted to other areas.

Sources have told Fairfax Media that immense pressure being exerted on resources, particularly in some rural areas and parts of western Sydney where needs are greatest, with people suffering acute psychiatric crises often left without help until the problem escalates and police are called.

However, the government said it takes the problem extremely seriously and has introduced ongoing auditing to prevent the diversion of funds.